Surface Wettability and Electrical Resistance Analysis of Droplets on Indium-Tin-Oxide Glass Fabricated Using an Ultraviolet Laser System
Abstract
:1. Introduction
2. Fundamental Theory
3. Materials and Experimental Setup
3.1. Materials
3.2. Experimental Setup
3.2.1. Pattern Fabrication: UV Laser (Wavelength- 355 nm) Processing
3.2.2. Surface Morphology Observation and CA Measurement
3.2.3. Experimental Process
- Step (I):
- AutoCAD (2017, Autodesk, San Rafael, CA, USA) was used to design the writing path of the laser spot. The left line and ablated line width of the ITO film were the same dimension, either 70, 90, 110, or 130 μm.
- Step (II):
- The parameters, such as the power and pulse repetition frequency of the laser system, were fixed, and the scanning speed and repetition times were adjusted to generate the comb-pattern microstructures with varying surface roughness and depth.
- Step (III):
- A 3D confocal microscope was used to measure the edge contour, line depth, and the morphology of the microstructures, and we analyzed the relationship of the depth and surface roughness of the ablated lines with the various repetition times and scanning speeds during laser treatment. The surface roughness is reported as mean height (Sa) and root mean square height (Sq). The Sa and Sq were defined by the average value and root mean square along the sampling area, respectively. In addition, the roughness of ablated line was also measured and defined as Ra (mean height) and Rq (root mean square).
- Step (IV):
- A digital microscope was set up to acquire a cross-section image of the droplet. Before acquiring the droplet image, we used the block gauge with an angle of 30°, 60°, and 90° to acquire the image and analyze the angle for the calibration process (Figure 5).
- Step (V):
- After the calibration, we placed the ITO glass on the stage in front of the digital microscope and added a droplet of deionized water on the microstructure region of the ITO glass surface. Each experimental parameter was repeated three times, and the volume of the droplet was determined in the first experiment. In addition, an electrical charge was exerted on the pad to observe the deformation of the droplet and investigate the variation in the CA. The relationship between the CA, surface roughness, ablated line pitch, and depth of the ITO film was analyzed to obtain the optimal parameters of the microstructure for enhancing the CA and generating a spherical droplet for biochip application.
4. Experimental Results and Discussion
4.1. Effect of Droplet Volume on CA
4.2. Effect of Scanning Speed on CA and Line Roughness
4.3. Effect of Line Pitch and Laser Scanning Speed on CA
4.4. Effect of Repetition Times on CA
4.5. Effect of Electric Field on CA
5. Conclusions
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Scanning Speed (mm/s) | 500 | 750 | 1000 | 1250 | 1500 |
---|---|---|---|---|---|
Ra (μm) | 0.292 | 0.290 | 0.453 | 0.493 | 0.573 |
Rq (μm) | 0.399 | 0.411 | 0.619 | 0.652 | 0.741 |
Line Width and Pitch (μm) | 70 | 90 | 110 | 130 |
---|---|---|---|---|
Sa (μm) | 0.635 | 0.632 | 0.518 | 0.679 |
Sq (μm) | 0.793 | 0.788 | 0.660 | 0.846 |
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Tsai, H.-Y.; Hsu, C.-N.; Li, C.-R.; Lin, Y.-H.; Hsiao, W.-T.; Huang, K.-C.; Yeh, J.A. Surface Wettability and Electrical Resistance Analysis of Droplets on Indium-Tin-Oxide Glass Fabricated Using an Ultraviolet Laser System. Micromachines 2021, 12, 44. https://doi.org/10.3390/mi12010044
Tsai H-Y, Hsu C-N, Li C-R, Lin Y-H, Hsiao W-T, Huang K-C, Yeh JA. Surface Wettability and Electrical Resistance Analysis of Droplets on Indium-Tin-Oxide Glass Fabricated Using an Ultraviolet Laser System. Micromachines. 2021; 12(1):44. https://doi.org/10.3390/mi12010044
Chicago/Turabian StyleTsai, Hsin-Yi, Chih-Ning Hsu, Cheng-Ru Li, Yu-Hsuan Lin, Wen-Tse Hsiao, Kuo-Cheng Huang, and J. Andrew Yeh. 2021. "Surface Wettability and Electrical Resistance Analysis of Droplets on Indium-Tin-Oxide Glass Fabricated Using an Ultraviolet Laser System" Micromachines 12, no. 1: 44. https://doi.org/10.3390/mi12010044
APA StyleTsai, H.-Y., Hsu, C.-N., Li, C.-R., Lin, Y.-H., Hsiao, W.-T., Huang, K.-C., & Yeh, J. A. (2021). Surface Wettability and Electrical Resistance Analysis of Droplets on Indium-Tin-Oxide Glass Fabricated Using an Ultraviolet Laser System. Micromachines, 12(1), 44. https://doi.org/10.3390/mi12010044